INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Common Source of Automotive Vibration?

Common Source of Automotive Vibration?

(OP)
For any vehicle, where would you find the highest vibration?

I'm testing out an accelerometer that will be used to wake up electronics.  

RE: Common Source of Automotive Vibration?

If everything else is balanced then the engine is always a major source of cyclical vibration.  

peace
Fe

RE: Common Source of Automotive Vibration?

top of the cylinder head (assuming vertical in line engine)this will capture the firing induced acceleration

www.priamengineering.co.uk

RE: Common Source of Automotive Vibration?

If you just want to wake up the stereo system when someone is getting ready to leave, look at the door switch position or the striker vibration.
 

RE: Common Source of Automotive Vibration?

(OP)
I'm trying to make a test setup where my chemical sensor will make a measurement a certain time after the vehicle has moved/or has not moved. But I want this to be portable for different vehicles w/o having to mess with the vehicle electronics.

For vibrations in the engine, should I expect things like timing belts to remain rpm independent as opposed to cylinders?

As for environment induced vibrations, what components would likely be affected? Or does the suspension system dampen everything out?

 

RE: Common Source of Automotive Vibration?

"timing belts to remain rpm independent as opposed to cylinders"

Huh?  A well adjusted timing belt runs at the same rpm as the engine, since it's intimately connected to it.

"what components would likely be affected"

There really ought not be any, since vibration reduces life.  There's a general vibration environment, and as mentioned a couple times already, the engine itself is a large part of that.

If you don't want to alter the car, then why not use a clip-on spark plug wire sensor?  Not only will you get an indication of engine rpm, but also timing.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize

RE: Common Source of Automotive Vibration?

(OP)
Ahh, I will look definitely look into that.

RE: Common Source of Automotive Vibration?

Strictly speaking the car can be moved without the engine running, and the engine can run without the the car moving. I admit these are not very common but if you want an ironclad method of measuring motion independent of the cars systems then you need GPS.  

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies  http://eng-tips.com/market.cfm?

RE: Common Source of Automotive Vibration?

the engine running w/o the car moving is very common...
 

RE: Common Source of Automotive Vibration?

the engine running w/o the car moving is very common...

Yes, around here we use the oxymoron "rush hour!"

RE: Common Source of Automotive Vibration?

Ain't that the truth.

Nonetheless, the "chemical sensor" might still be able to make a decent measurement, with the engine spark sensor doing a minimum of processing to validate a time series of ignition pulses as being consistent with normal driving.  Presumably, measurement system will be making measurements over the course of days or weeks, so a singular instance of odd behavior shouldn't mess things up too much.  If these erroneous events happen too often, then the car chosen for measurement was a bad choice.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies
Chinese prisoner wins Nobel Peace Prize

RE: Common Source of Automotive Vibration?

Thought.
If the engine is not engaged to the transmission and drivetrain and it is "revved" would it not exhibit more vibration than the situation where the vehicle is driving and we rev the engine?
I never thought of this before, just a thought.
The inertia of he drivetrain components may change the amplitude and or dampen the engine case vibration.  

peace
Fe

RE: Common Source of Automotive Vibration?

If the car has ABS, the wheel sensors could sense the car moving so long as the car had not been jacked up and placed on a separate device like a tilt bed truck or a vehicular ferry.

Wheel sensors and spark plug sensor combined would sense engine running and wheels turning and that covers all but the most bizarre circumstances, like sliding along an ice covered road with engine running and brakes locked.  

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
 

RE: Common Source of Automotive Vibration?

Simplest solution, perhaps not 'smart' enough for this application, is measuring voltage at the cigarette lighter, excuse me accessory, socket.
When the voltage goes from 12 or less to 13 or more, the engine has started, and chances are the car will move soon.
When the voltage goes back down to 12 or less, the engine has stopped, and chances are the car is not moving.

 

Mike Halloran
Pembroke Pines, FL, USA

RE: Common Source of Automotive Vibration?

Mike. That is an astoundingly simple test for engine running and from the cabin with not one spot of soil on the hands.

A simple accelerometer like in fancy smart phones might detect motion to a sufficient degree.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
 

RE: Common Source of Automotive Vibration?

Or if it's my car, simply determine if there's voltage at the cigarette lighter... if not, the engine is off.

Dan - Owner
http://www.Hi-TecDesigns.com

RE: Common Source of Automotive Vibration?

On my Scion that would tell you whether the ignition switch was in "on" or "acc" positions but wouldn't tell you about the status of the engine.  

On my Explorer that would tell you that you'd found the hole...there's always voltage in there if nothing's broken.



 

RE: Common Source of Automotive Vibration?

Isaac

The voltage varies when the alternator is charging as the engine runs.

I know modern Hondas s cut back the alternator voltage output once the battery is charged however I do not think that is common on other brands yet.

Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
 

RE: Common Source of Automotive Vibration?

The voltage also seems to get fairly high when it's hot out, but you're right - I was thinking just about the switching of the power supply to the socket, not how many volts would be read by the meter.  

 

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close